There are various cutting technologies known to cut parts out of a piece of material and the present invention relates to what here is called beam cutting technology. Beam cutting is defined as having some kind of beam as the cutting means, such as laser cutting, plasma cutting, ion beam cutting, flame or torch cutting, water cutting, pellet cutting or air cutting. This is not to be confused with mechanical cutting where the cutting means is a mechanical member such as a cutting blade or a rotating cutting head.
It is traditionally known to use a work plan optimization tool based on nesting part placement methods to place out the parts that are to be cut out of a piece of material. As commonly used today, a set of parts cut by a beam cutting technology is cut by making a complete contour around each individual part. Each part needs to be designed by the constructor such that it may be cut as a separate part and positioned with a safety distance to adjacent parts during cutting. With such traditional cutting methods it is not possible to place the parts close to each other without any safety distance, since this would result in the cutting beam cutting the same cut twice, whereby the parts would risk being deformed, damaged or the tolerances not met. The size of the safety distances varies depending on used material and used cutting technology, but a normal safety distance between parts is 5-20 mm.
Thus, with any kind of beam cutting technology there is a huge problem with waste, and a normal production reliable cutting plan results in 20-50 percent waste. It is thus desirable to minimize the distance between adjacent parts in order to reduce the waste material.
In WO 2011/042058 A1 a method is disclosed for machine cutting of several parts out of a piece of material using a beam cutting technology. The invention disclosed therein provides a set of controlling rules and variables for forming of a cluster of parts with free form shapes, the parts being positioned so close to each other so that one cut from the cutting beam is found between adjacent parts whenever the shape of said parts allows it. This method reduces the need of safety distances between individual parts and thus reduces the waste material between the parts substantially.